The present invention is concerned with water soluble azole containing ethers as broad-spectrum antifungals and their preparation; it further relates to compositions comprising them, as well as their use as a medicine.
Systemic fungal infections in man are relatively rare in temperate countries and many of the fungi that can become pathogenic normally live commensally in the body or are common in the environment. The past few decades have witnessed an increasing incidence of numerous life-threatening systemic fungal infections world-wide and these now represent a major threat to many susceptible patients, particularly those already hospitalized. Most of the increase can be attributed to improved survival of immuno-compromised patients and the chronic use of antimicrobial agents. Moreover, the flora typical of many common fungal infections is also changing and this is presenting an epidemiological challenge of increasing importance. Patients at greatest risk include those with impaired immune functioning, either directly as a result of immunosuppression from cytotoxic drugs or HIV infection, or secondary to other debilitating diseases such as cancer, acute leukaemia, invasive surgical techniques or prolonged exposure to antimicrobial agents. The most common systemic fungal infections in man are candidosis, aspergillosis, histoplasmosis, coccidioidomycosis, paracoccidioidomycosis, blastomycosis and cryptococcosis.
Antifungals such as ketoconazole, itraconazole and fluconazole are employed for the treatment and prophylaxis of systemic fungal infections in immuno-compromised patients. However, concern is growing about fungal resistance to some of these agents, especially these with a relatively narrow spectrum, e.g. fluconazole. Worse still, it is recognized in the medical world that about 40% of the people suffering from severe systemic fungal infections are hardly, or not at all, able to receive medication via oral administration. This inability is due to the fact that such patients are in coma or suffer from severe gastroparesis. Hence, the use of insoluble or sparingly soluble antifungals such as itraconazole, that are difficult to administer intravenously, is heavily impeded in this group of patients.
Also the treatment of onychomycosis, i.e. fungal infection of the nails, may well be served by potent water soluble antifungals. It is long desired to treat onychomycosis via the transungual route. The problem that then arises is to ensure that the antifungal agents will penetrate into and beneath the nail. Mertin and Lippold (J. Pharm.
Pharmacol. (1997), 49, 30-34) stated that in order to screen for drugs for topical application to the nail plate, attention has to be paid mainly to the water solubility of the compound. The maximum flux through the nail is beneficially influenced by increasing the water solubility of the antifungal. Of course, efficacy in treating onychomycosis via the transungual route is also dependent on the potency of the antifungal.
Consequently, there is a need for new antifungals, preferably broad-spectrum antifungals, against which there is no existing resistance and which can be administered intravenously or transungually. Preferably the antifungal should also be available in a pharmaceutical composition suitable for oral administration. This enables the physician to continue treatment with the same drug after the patient has recovered from the condition which required intravenous or transungual administration of said drug.
U.S. Pat. No. 4,267,179 discloses heterocyclic derivatives of (4-phenylpiperazin-1-yl-aryloxy-methyl-1,3-dioxolan-2-yl)-methyl-1H-imidazoles and 1H-1,2,4-triazoles useful as antifungal agents. Said patent encompasses itraconazole, which is available as a broad-spectrum antifungal on a world-wide basis.
EP-A-0, 118,138 and EP-A-0,228,125 disclose 4-[4-[4-[4-[[2-aryl-2-azolyl-1,3dioxolan-4-yl]methoxy]phenyl]-1-piperazinyl]phenyl]-2,4-dihydro-2-alkyloxyalkyl-3H-1,2,4-triazol-3-one derivatives as antifungals. WO 95/17407 discloses tetrahydrofuran antifungals as well as WO 96/38443 and WO 97/00255. The latter two publications disclose tetrahydrofuran antifungals, which are taught to be soluble and/or suspendible in an aqueous medium suitable for intravenous administration, containing substitution groups readily convertible in vivo into hydroxy groups.
Unexpectedly, the compounds of the present invention are potent broad-spectrum antifungals with good water solubility.
The present invention concerns compounds of formula 
the N-oxide forms, the salts, the quaternary amines and stereochemically isomeric forms thereof, wherein
D represents a radical of formula 
xe2x80x83wherein the dotted line represents the bond attaching D to the remainder of the compound of formula (1);
X is N or CH;
R3 is hydrogen or halo;
R4 is halo;
xe2x80x94Axe2x80x94Bxe2x80x94 represents a bivalent radical of formula
xe2x80x94Nxe2x95x90CHxe2x80x94xe2x80x83xe2x80x83(i),
xe2x80x94CHxe2x95x90Nxe2x80x94xe2x80x83xe2x80x83(ii),
xe2x80x94CHxe2x95x90CHxe2x80x94xe2x80x83xe2x80x83(iii),
xe2x80x94CH2xe2x80x94CH2xe2x80x83xe2x80x83(iv),
wherein one hydrogen atom in the radicals (i) and (ii) may be replaced by a C1-4alkyl radical and one or more hydrogen atoms in radicals (iii) and (iv) may be replaced by a C1-4alkyl radical;
Alk represents C1-6alkanediyl;
Y represents C1-6alkanediyl optionally substituted with one or two substituents selected from halo, hydroxy, mercapto, C1-4alkyloxy, C1-4alkylthio, aryloxy, arylthio, arylC1-4alkyloxy, arylC1-4alkylthio, cyano, amino, mono- or di(C1-4alkyl)amino, mono- or di(aryl)amino, mono- or di(arylC1-4alkyl)amino, C1-4alkyloxycarbonylamino, benzyloxycarbonylamino, aminocarbonyl, carboxyl, C1-4alkyloxycarbonyl, guanidinyl, aryl and Het;
R1 represents hydrogen, C1-4alkyl or arylC1-6alkyl; R2 represents hydrogen, C1-4alkyl or arylC1-6alkyl; or R1 and R2 may be taken together to form a heterocyclic radical selected from morpholinyl, pyrrolidinyl, piperidinyl, homopiperidinyl, piperazinyl or phthalimid-1-yl; said heterocyclic radical may optionally be substituted with C1-4alkyl, aryl, Het, arylC1-4alkyl, HetC1-4alkyl, hydroxyC1-4alkyl, amino, mono- or di(C1-4alkyl)amino, aminoC1-4alkyl, mono- or di(C1-4alkyl)aminoC1-4alkyl, carboxyl, aminocarbonyl, C1-4alkyloxycarbonyl; C1-4alkyloxycarbonylamino or mono- or di(C1-4alkyl)aminocarbonyl;
aryl represents phenyl, naphthalenyl, 1,2,3,4-tetrahydro-naphthalenyl, indenyl or indanyl; each of said aryl groups may optionally be substituted with one or more substituents selected from halo, C1-4alkyl, hydroxy, C1-4alkyloxy, nitro, amino, trifluoromethyl, hydroxyC1-4alkyl, C1-4alkyloxyC1-4alkyl, aminoC1-4alkyl, mono- or di(C1-4alkyl)aminoC1-4alkyl;
Het represents a monocyclic or bicyclic heterocyclic radical; said monocyclic heterocyclic radical being selected from the group piperazinyl, homopiperazinyl, 1,4-dioxanyl, morpholinyl, thiomorpholinyl, pyridyl, piperidinyl, homopiperidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, triazolyl, pyranyl, tetrahydropyranyl, imidazolyl, imidazolinyl, imidazolidinyl, pyrazolyl, pyrazolinyl, pyrazolidinyl, thiazolyl, thiazolidinyl, isothiazolyl, oxazolyl, oxazolidinyl, isoxazolyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, furanyl, tetrahydrofuranyl, thienyl, thiolanyl, dioxolanyl; said bicyclic heterocyclic radical being selected from the group quinolinyl, 1,2,3,4-tetrahydroquinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, phtalazinyl, cinnolinyl, chromanyl, thiochromanyl, 2H-chromenyl, 1,4-benzodioxanyl, indolyl, isoindolyl, indolinyl, indazolyl, purinyl, pyrrolopyridinyl, furanopyridinyl, thienopyridinyl, benzothiazolyl, benzoxazolyl, benzisothiazolyl, benzisoxazolyl, benzimidazolyl, benzofuranyl, benzothienyl; whereby each of said mono- or bicyclic heterocycle may optionally be substituted with one or where possible more substituents selected from halo, C1-4alkyl, hydroxy, C1-4alkyloxy, nitro, amino, trifluoromethyl, hydroxyC1-4alkyl, C1-4alkyloxy-C1-4alkyl, aminoC1-4alkyl, mono- or di(C1-4alkyl)aminoC1-4alkyl, aryl or arylC1-4alkyl.
As used in the foregoing definitions and hereinafter halo defines fluoro, chloro, bromo and iodo; C1-4alkyl as a group or part of a group encompasses the straight and branched chain saturated hydrocarbon radicals having from 1 to 4 carbon atoms such as, for example, methyl, ethyl, propyl, butyl and the like; C1-6alkyl as a group or part of a group encompasses the straight and branched chain saturated hydrocarbon radicals as defined in C1-4alkyl as well as the higher homologues thereof containing 5 or 6 carbon atoms such as, for example, pentyl or hexyl; C1-6alkanediyl encompasses the straight and branched chain saturated bivalent hydrocarbon radicals having from 1 to 6 carbon atoms such as, for example, methylene, 1,2-ethanediyl, 1,3-propanediyl, 1,4-butanediyl, 1,5-pentanediyl, 1,6-hexanediyl, 1,2-propanediyl, 1,2-butanediyl, 2,3-butanediyl and the like; C2-3alkanediyl encompasses the straight and branched chain saturated bivalent hydrocarbon radicals having 2 or 3 carbon atoms such as, for example, 1,2-ethanediyl, 1,2-propanediyl and 1,3-propanediyl.
For therapeutic use, salts of the compounds of formula (I) are those wherein the counterion is pharmaceutically acceptable. However, salts of acids and bases which are non-pharmaceutically acceptable may also find use, for example, in the preparation or purification of a pharmaceutically acceptable compound. All salts, whether pharmaceutically acceptable or not are included within the ambit of the present invention.
The pharmaceutically acceptable addition salts as mentioned hereinabove are meant to comprise the therapeutically active non-toxic acid addition salt forms which the compounds of formula (I) are able to form. The latter can conveniently be obtained by treating the base form with such appropriate acids as inorganic acids, for example, hydrohalic acids, e.g. hydrochloric, hydrobromic and the like; sulfuric acid; nitric acid; phosphoric acid and the like; or organic acids, for example, acetic, propanoic, hydroxyacetic, 2-hydroxypropanoic, 2-oxopropanoic, oxalic, malonic, succinic, maleic, fumaric, malic, tartaric, 2-hydroxy-1,2,3-propanetricarboxylic, methanesulfonic, ethanesulfonic, benzenesulfonic, 4-methylbenzenesulfonic, cyclohexanesulfamic, 2-hydroxybenzoic, 4-amino-2-hydroxybenzoic and the like acids. Conversely the salt form can be converted by treatment with alkali into the free base form.
The compounds of formula (I) containing acidic protons may be converted into their therapeutically active non-toxic metal or amine addition salt forms by treatment with appropriate organic and inorganic bases. Appropriate base salt forms comprise, for example, the ammonium salts, the alkali and earth alkaline metal salts, e.g. the lithium, sodium, potassium, magnesium, calcium salts and the like, salts with organic bases, e.g. primary, secondary and tertiary aliphatic and aromatic amines such as methylamine, ethylamine, propylamine, isopropylamine, the four butylamine isomers, dimethylamine, diethylamine, diethanolamine, dipropylamine, diisopropylamine, di-n-butylamine, pyrrolidine, piperidine, morpholine, trimethylamine, triethylamine, tripropylamine, quinuclidine, pyridine, quinoline and isoquinoline, the benzathine, N-methyl-D-glucamine, 2-amino-2-(hydroxymethyl)-1,3-propanediol, hydrabamine salts, and salts with amino acids such as, for example, arginine, lysine and the like. Conversely the salt form can be converted by treatment with acid into the free acid form. The term addition salt also comprises the hydrates and solvent addition forms which the compounds of formula (I) are able to form. Examples of such forms are e.g. hydrates, alcoholates and the like.
The term xe2x80x9cquaternary aminexe2x80x9d as used hereinbefore defines the quaternary ammonium salts which the compounds of formula (I) are able to form by reaction between a basic nitrogen of a compound of formula (I) and an appropriate quaternizing agent, such as, for example, an optionally substituted alkylhalide, arylhalide or arylalkylhalide, e.g. methyliodide or benzyliodide. Other reactants with good leaving groups may also be used, such as alkyl trifluoromethanesulfonates, alkyl methanesulfonates, and alkyl p-toluenesulfonates. A quaternary amine has a positively charged nitrogen. Pharmaceutically acceptable counterions include chloro, bromo, iodo, trifluoroacetate and acetate. The counterion of choice can be made using ion exchange resin columns.
The term xe2x80x9cstereochemically isomeric formsxe2x80x9d as used hereinbefore defines all the possible stereoisomeric forms in which the compounds of formula (I) exist, thus, also including all enantiomers, enantiomeric mixtures and diastereomeric mixtures. Unless otherwise mentioned or indicated, the chemical designation of compounds denotes the mixture of all possible stereoisomeric forms, said mixtures containing all diastereomers and enantiomers of the basic molecular structure. The same applies to the intermediates as described herein, used to prepare end products of formula (I).
Pure stereoisomeric forms of the compounds and intermediates as mentioned herein are defined as isomers substantially free of other enantiomeric or diastereomeric forms of the same basic molecular structure of said compounds or intermediates. In particular, the term xe2x80x98stereoisomerically purexe2x80x99 being equivalent to xe2x80x98chirally purexe2x80x99 concerns compounds or intermediates having a stereoisomeric excess of at least 80% (i.e. minimum 90% of one isomer and maximum 10% of the other possible isomers) up to a stereoisomeric excess of 100% (i.e. 100% of one isomer and none of the other), more in particular, compounds or intermediates having a stereoisomeric excess of 90% up to 100%, even more in particular having a stereoisomeric excess of 94% up to 100% and most in particular having a stereoisomeric excess of 97% up to 100%. The terms xe2x80x98enantiomerically purexe2x80x99 and xe2x80x98diastereomerically purexe2x80x99 should be understood in a similar way, but then having regard to the enantiomeric excess, respectively the diastereomeric excess of the mixture in question.
The terms cis and trans are used herein in accordance with Chemical Abstracts nomenclature and refer to the position of the substituents on a ring moiety, more in particular on the tetrahydrofuran ring or the dioxolane ring in the compounds of formula (I). For instance, when establishing the cis or trains configuration of a tetrahydrofuran or dioxolane ring in a radical of formula (D1), (D2), (D3) or (D4), the substituent with the highest priority on the carbon atom in the 2 position of the tetrahydrofuran or dioxolane ring, and the substituent with the highest priority on the carbon atom in the 4 position of the tetrahydrofuran or dioxolane ring in the radicals of formula (D1), (D2) or (D4) or the 5 position of the tetrahydrofuran ring in the radical of formula (D3) are considered (the priority of a substituent being determined according to the Cahn-Ingold-Prelog sequence rules). When said two substituents with highest priority are at the same side of the ring then the configuration is designated cis, if not, the configuration is designated trans.
The compounds of formula (I) all contain at least 2 asymmetric centers which may have the R- or S-configuration. As used herein, the stereochemical descriptors denoting the stereochemical configuration of each of the 2 or more asymmetric centers are also in accordance with Chemical Abstracts nomenclature.
Of some compounds of formula (I) and of intermediates used in their preparation, the absolute stereochemical configuration was not experimentally determined. In those cases the stereoisomeric form which was first isolated is designated as xe2x80x9cAxe2x80x9d and the second as xe2x80x9cBxe2x80x9d, without further reference to the actual stereochemical configuration. However, said xe2x80x9cAxe2x80x9d and xe2x80x9cBxe2x80x9d stereoisomeric forms can be unambiguously characterized by for instance their optical rotation in case xe2x80x9cAxe2x80x9d and xe2x80x9cBxe2x80x9d have an enantiomeric relationship. A person skilled in the art is able to determine the absolute configuration of such compounds using art-known methods such as, for example, X-ray diffraction. In case xe2x80x9cAxe2x80x9d and xe2x80x9cBxe2x80x9d are stereoisomeric mixtures, they can be further separated whereby the respective first fractions isolated are designated xe2x80x9cA1xe2x80x9d and xe2x80x9cB1xe2x80x9d and the second as xe2x80x9cA2xe2x80x9d and xe2x80x9cB2xe2x80x9d, without further reference to the actual stereochemical configuration.
The N-oxide forms of the present compounds are meant to comprise the compounds of formula (I) wherein one or several nitrogen atoms are oxidized to the so-called N-oxide.
Some of the compounds of formula (I) may also exist in their tautomeric form. Such forms although not explicitly indicated in the above formula are intended to be included within the scope of the present invention.
Whenever used hereinafter, the term xe2x80x9ccompounds of formula (I)xe2x80x9d is meant to also include their N-oxide forms, their salts, their quaternary amines and their stereochemically isomeric forms. Of special interest arc those compounds of formula (I) which are stereochemically pure.
An interesting group of compounds are those compounds of formula (I) wherein xe2x80x94Alkxe2x80x94 is a bivalent radical of formula 
wherein the carbon atom marked with one asterisk is attached to the nitrogen atom and the carbon atom marked with two asterisks is attached to the oxygen atom.
Also interesting are those compounds of formula (I) wherein D is a radical of formula D1or D2, in particular D1. Suitably, R3 and R4 are both a halogen, more in particular a chloro or fluoro atom, and X is a nitrogen atom.
Further xe2x80x94Axe2x80x94Bxe2x80x94 suitably is a radical of formula (ii).
A particular group of compounds are those compounds of formula (I) wherein Y is C1-6alkanediyl optionally substituted with aryl; more in particular, C2-3alkanediyl optionally substituted with aryl.
A preferred group of compounds are those compounds of formula (1) wherein D is a radical of formula D1, X is a nitrogen atom, R3 and R4 are both a halogen, xe2x80x94Alkxe2x80x94 is a bivalent radical of formula

wherein the carbon atom marked with an asterisk is attached to the nitrogen atom and the carbon atom marked with two asterisks is attached to the oxygen atom and Y is C2-3alkanediyl optionally substituted with aryl.
The compounds of the present invention can be prepared by reacting an intermediate of formula (II) wherein W1 is a suitable leaving group such as, for example, a halogen, e.g. iodo, an arylsulfonyloxy or an alkanesulfonyloxy group, e.g. p-toluenesulfonyloxy, naphthylsulfonyloxy or methanesulfonyloxy, with an intermediate of formula (III) in a reaction-inert solvent such as, for example, N,N-dimethylformamide, N,N-dimethylacetamide, 1-methyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, sulfolane or the like, and in the presence of a suitable base such as, for example, sodium hydroxide or sodium hydride. 
In this and the following preparations, the reaction products may be isolated from the reaction medium and, if necessary, further purified according to methodologies generally known in the art such as, for example, extraction, crystallization, trituration and chromatography. In particular, stereoisomers can be isolated chromatographically using a chiral stationary phase such as, for example, Chiralpak AD (amylose 3,5 dimethylphenyl carbamate) or Chiralpak AS, both purchased from Daicel Chemical Industries, Ltd, in Japan.
Compounds of formula (I) may also be prepared by N-alkylating an intermediate of formula (IV) with an intermediate of formula (V) wherein W2 is a suitable leaving group such as, for example, a halogen, and in case R1 and/or R is hydrogen, the primary or secondary amine group is protected with a protective group P such as, for example, a C1-4alkyloxycarbonyl group or a benzyl group, in a reaction-inert solvent such as, for example, dimethylsulfoxide, in the presence of a base such as, for example, potassium hydroxide. In case the amine was protected, art-known deprotection techniques can be employed to arrive at compounds of formula (I) after the N-alkylation reaction. 
Compounds of formula (I) may also be prepared by reacting an intermediate of formula (VI) with an intermediate of formula (VII) wherein W3 is a suitable leaving group such as, for example, a halogen, an arylsulfonyloxy or an alkanesulfonyloxy group, e.g. p-toluenesulfonyloxy, naphthylsulfonyloxy or methanesulfonyloxy, optionally in the presence of a suitable base such as, for example, sodium hydride, and optionally in a reaction-inert solvent such as, for example, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, 1-methyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, sulfolane or the like. In case R1 and/or R2 is hydrogen, the primary or secondary amine group may be protected with a protective group P such as, for example, a C1-4alkyloxycarbonyl group or a benzyl group, and after the O-alkylation reaction, art-known deprotection techniques can be employed to arrive at compounds of formula (I) 
The compounds of formula (I) may also be converted into each other following art-known transformations.
Compounds of formula (I) containing a C1-4alkyloxycarbonylamino moiety may be converted to compounds of formula (I) containing the corresponding amino moiety using art-known techniques such as, for example, reaction in dichloromethane and in the presence of trifluoroacetic acid.
Compounds of formula (I) containing a primary amine may be mono-methylated by first protecting the primary amine with a suitable protecting group such as, for example, an arylalkyl group, e.g. benzyl; and subsequently methylating the secondary amine using art-known methylation techniques such as, for example, reaction with paraformaldehyde. The thus obtained tertiary amine may be deprotected using art-known deprotection techniques such as, for example, reaction with hydrogen in tetrahydrofuran or methanol and in the presence of a catalyst such as, for example palladium-on-charcoal, thus obtaining the desired methylated secondary amine.
The compounds of formula (I) may also be converted to the corresponding N-oxide forms following art-known procedures for converting a trivalent nitrogen into its N-oxide form. Said N-oxidation reaction may generally be carried out by reacting the starting material of formula (I) with an appropriate organic or inorganic peroxide. Appropriate inorganic peroxides comprise, for example, hydrogen peroxide, alkali metal or earth alkaline metal peroxides, e.g. sodium peroxide, potassium peroxide; appropriate organic peroxides may comprise peroxy acids such as, for example, benzenecarboperoxoic acid or halo substituted benzenecarboperoxoic acid, e.g. 3-chlorobenzenecarboperoxoic acid, peroxoalkanoic acids, e.g. peroxoacetic acid, alkylhydroperoxides, e.g. tert-butyl hydroperoxide. Suitable solvents are, for example, water, lower alkanols, e.g. ethanol and the like, hydrocarbons, e.g. toluene, ketones, e.g. 2-butanone, halogenated hydrocarbons, e.g. dichloromethane, and mixtures of such solvents.
Some of the intermediates and starting materials used in the above reaction procedures are commercially available, or may be synthesized according to procedures described elsewhere, e.g. U.S. Pat. No. 4,619,931, U.S. Pat. No. 4,791,111, U.S. Pat. No. 4,931,444, U.S. Pat. No. 4,267,179 and WO 98/34934.
Pure stereoisomeric forms of the compounds and the intermediates of this invention may be obtained by the application of art-known procedures. Diastereomers may be separated by physical separation methods such as selective crystallization and chromatographic techniques, e.g. liquid chromatography using chiral stationary phases.
Enantiomers may be separated from each other by the selective crystallization of their diastereomeric salts with optically active acids. Alternatively, enantiomers may be separated by chromato-graphic techniques using chiral stationary phases. Said pure stereoisomeric forms may also be derived from the corresponding pure stereoisomeric forms of the appropriate starting materials, provided that the reaction occurs stereo-selectively or stereospecifically. Preferably if a specific stereoisomer is desired, said compound will be synthesized by stereoselective or stereospecific methods of preparation. These methods will advantageously employ chirally pure starting materials. Stereoisomeric forms of the compounds of formula (1) are obviously intended to be included within the scope of the invention.
The chirally pure forms of the compounds of formula (I) form a preferred group of compounds. It is therefore that the chirally pure forms of the intermediates of formula (II), (III) and (VI), their N-oxide forms, their salt forms and their quaternary amines are particularly useful in the preparation of chirally pure compounds of formula (I). Also enantiomenc mixtures and diastereomeric mixtures of intermediates of formula (II), (III) and (VI) are useful in the preparation of compounds of formula (I) with the corresponding configuration.
The compounds of formula (I), the salts, the quaternary amines and the stereochemically isomeric forms thereof are useful agents for combating fungi in vivo. The present compounds are broad-spectrum antifungals. They are active against a wide variety of fungi, such as Candida spp., e.g. Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, Candida kefyr, Candida tropicalis; Aspergillus spp., e.g. Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus; Cryptococcus neoformans; Sporothrix schenckii; Fonsecaea spp.; Epidermophyton floccosum; Microsporum canis; Trichophyton spp.; Fusarium spp.; and several dematiaceous hyphomycetes. Of particular interest is the improved activity of some of the present compounds against Fusarium spp.
In vitro experiments, including the determination of the fungal susceptibility of the present compounds as described in the pharmacological example hereinafter, indicate that the compounds of formula (I) have a favourable intrinsic inhibitory capacity on fungal growth in for instance Candida albicans. Other in vitro experiments such as the determination of the effects of the present compounds on the sterol synthesis in, for instance, Candida albicans, also demonstrate their antifungal potency. Also in vivo experiments in several mouse, guinea-pig and rat models show that, after both oral and intravenous administration, the present compounds are potent antifungals.
An additional advantage of some of the present compounds is that they are not only fungistatic, as most of the known azole antifungals, but are also fungicidal at acceptable therapeutic doses against many fungal isolates.
The compounds of the present invention are chemically stable and have a good oral availability.
The solubility profile in aqueous solutions of the compounds of formula (I) makes them suitable for intravenous administration. Particularly interesting compounds are those compounds of formula (I) having a water-solubility of at least 0.1 mg/ml at a pH of at least 4, preferably, a water-solubility of at least 1 mg/ml at a pH of at least 4, and more preferred a water-solubility of at least 5 mg/ml at a pH of at least 4.
In view of the utility of the compounds of formula (I), there is provided a method of treating warm-blooded animals, including humans, suffering from fungal infections. Said method comprises the systemic or topical administration of an effective amount of a compound of formula (I), a N-oxide form, a salt, a quaternary amine or a possible stereoisomeric form thereof, to warm-blooded animals, including humans. Hence, compounds of formula (I) are provided for use as a medicine, in particular, the use of a compound of formula (I) in the manufacture of a medicament useful in treating fungal infections is provided.
The present invention also provides compositions for treating or preventing fungal infections comprising a therapeutically effective amount of a compound of formula (I) and a pharmaceutically acceptable carrier or diluent.
In view of their useful pharmacological properties, the subject compounds may be formulated into various pharmaceutical forms for administration purposes. To prepare the pharmaceutical compositions of this invention, a therapeutically effective amount of a particular compound, in base or addition salt form, as the active ingredient is combined in intimate admixture with a pharmaceutically acceptable carrier, which.carrier may take a wide variety of forms depending on the form of preparation desired for administration. These pharmaceutical compositions are desirably in unitary dosage form suitable, preferably, for administration orally, rectally, topically, percutaneously, transungually or by parenteral injection. For example, in preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed, such as, for example, water, glycols, oils, alcohols and the like in the case of oral liquid preparations such as suspensions, syrups, emulsions, elixirs and solutions: or solid carriers such as starches, sugars, kaolin, lubricants, binders, disintegrating agents and the like in the case of powders, pills, capsules and tablets. Because of their ease in administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are obviously employed. As appropriate compositions for topical application there may be cited all compositions usually employed for topically administering drugs e.g. creams, gel, dressings, shampoos, tinctures, pastes, ointments, salves, powders and the like. In the compositions suitable for percutaneous administration, the carrier optionally comprises a penetration enhancing agent and/or a suitable wetting agent, optionally combined with suitable additives of any nature in minor proportions, which additives do not cause a significant deleterious effect to the skin. Said additives may facilitate the administration to the skin and/or may be helpful for preparing the desired compositions. These compositions may be administered in various ways, e.g., as a transdermal patch, as a spot-on, as an ointment.
Transungual compositions are in the form of a solution and the carrier optionally comprises a penetration enhancing agent which favours the penetration of the antifungal into and through the keratinized ungual layer of the nail. The solvent medium comprises water mixed with a co-solvent such as an alcohol having from 2 to 6 carbon atoms, e.g. ethanol.
For parenteral compositions, the carrier will usually comprise sterile water, at least in large part. Injectable solutions, for example, may be prepared in which the carrier comprises saline solution, glucose solution or a mixture of saline and glucose solution. Injectable suspensions may also be prepared in which case appropriate liquid carriers, suspending agents and the like may be employed. For parenteral compositions, also other ingredients, to aid solubility for example, e.g. cyclodextrins, may be included. Appropriate cyclodextrins are xcex1-, xcex2-, xcex3-cyclodextrins or ethers and mixed ethers thereof wherein one or more of the hydroxy groups of the anhydroglucose units of the cyclodextrin are substituted with C1-6alkyl, particularly methyl, ethyl or isopropyl, e.g. randomly methylated xcex2-CD; hydroxyC1-6alkyl, particularly hydroxyethyl, hydroxypropyl or hydroxybutyl; carboxyC1-6alkyl, particularly carboxymethyl or carboxyethyl; C1-6alkylcarbonyl, particularly acetyl. Especially noteworthy as complexants and/or solubilizers are xcex2-CD, randomly methylated xcex2-CD, 2,6-dimethyl-xcex2-CD, 2-hydroxyethyl-xcex2-CD, 2-hydroxyethyl-xcex3-CD, 2-hydroxypropyl-xcex3-CD and (2-carboxymethoxy)propyl-xcex2-CD, and in particular 2-hydroxypropyl-xcex2-CD (2-HP-xcex2-CD).
The term mixed ether denotes cyclodextrin derivatives wherein at least two cyclodextrin hydroxy groups are etherified with different groups such as, for example, hydroxy-propyl and hydroxyethyl.
The average molar substitution (M.S.) is used as a measure of the average number of moles of alkoxy units per mole of anhydroglucose. The average substitution degree (D.S.) refers to the average number of substituted hydroxyls per anhydroglucose unit. The M.S. and D.S. value can be determined by various analytical techniques such as nuclear magnetic resonance (NMR), mass spectrometry (MS) and infrared spectroscopy (IR). Depending on the technique used, slightly different values may be obtained for one given cyclodextrin derivative. Preferably, as measured by mass spectrometry, the M.S. ranges from 0.125 to 10 and the D.S. ranges from 0.125 to 3.
Other suitable compositions for oral or rectal administration comprise particles consisting of a solid dispersion comprising a compound of formula (I) and one or more appropriate pharmaceutically acceptable water-soluble polymers.
The term xe2x80x9ca solid dispersionxe2x80x9d used hereinafter defines a system in a solid state (as opposed to a liquid or gaseous state) comprising at least two components, in casu the compound of formula (I) and the water-soluble polymer, wherein one component is dispersed more or less evenly throughout the other component or components (in case additional pharmaceutically acceptable formulating agents, generally known in the art, are included, such as plasticizers, preservatives and the like). When said dispersion of the components is such that the system is chemically and physically uniform or homogenous throughout or consists of one phase as defined in thermo-dynamics, such a solid dispersion will be called xe2x80x9ca solid solutionxe2x80x9d. Solid solutions are preferred physical systems because the components therein are usually readily bioavailable to the organisms to which they are administered. This advantage can probably be explained by the ease with which said solid solutions can form liquid solutions when contacted with a liquid medium such as the gastro-intestinal juices. The ease of dissolution may be attributed at least in part to the fact that the energy required for dissolution of the components from a solid solution is less than that required for the dissolution of components from a crystalline or microcrystalline solid phase.
The term xe2x80x9ca solid dispersionxe2x80x9d also comprises dispersions which are less homogenous throughout than solid solutions. Such dispersions are not chemically and physically uniform throughout or comprise more than one phase. For example, the term xe2x80x9ca solid dispersionxe2x80x9d also relates to a system having domains or small regions wherein amorphous, microcrystalline or crystalline compound of formula (I), or amorphous, microcrystalline or crystalline water-soluble polymer, or both, are dispersed more or less evenly in another phase comprising water-soluble polymer, or compound of formula (I), or a solid solution comprising compound of formula (I) and water-soluble polymer. Said domains are regions within the solid dispersion distinctively marked by some physical feature, small in size, and evenly and randomly distributed throughout the solid dispersion.
Various techniques exist for preparing solid dispersions including melt-extrusion, spray-drying and solution-evaporation.
The solution-evaporation process comprises the following steps:
a) dissolving the compound of formula (I) and the water-soluble polymer in an appropriate solvent, optionally at elevated temperatures;
b) heating the solution resulting under point a), optionally under vacuum, until the solvent is evaporated. The solution may also be poured onto a large surface so as to form a thin film, and evaporating the solvent therefrom.
In the spray-drying technique, the two components are also dissolved in an appropriate solvent and the resulting solution is then sprayed through the nozzle of a spray dryer followed by evaporating the solvent from the resulting droplets at elevated temperatures.
The preferred technique for preparing solid dispersions is the melt-extrusion process comprising the following steps:
a) mixing a compound of formula (I) and an appropriate water-soluble polymer,
b) optionally blending additives with the thus obtained mixture,
c) heating and compounding the thus obtained blend until one obtains a homogenous melt,
d) forcing the thus obtained melt through one or more nozzles; and
e) cooling the melt till it solidifies.
The terms xe2x80x9cmeltxe2x80x9d and xe2x80x9cmeltingxe2x80x9d should be interpreted broadly. These terms not only mean the alteration from a solid state to a liquid state, but can also refer to a transition to a glassy state or a rubbery state, and in which it is possible for one component of the mixture to get embedded more or less homogeneously into the other. In particular cases, one component will melt and the other component(s) will dissolve in the melt thus forming a solution, which upon cooling may form a solid solution having advantageous dissolution properties.
After preparing the solid dispersions as described hereinabove, the obtained products can be optionally milled and sieved.
The solid dispersion product can be milled or ground to particles having a particle size of less than 600 xcexcm, preferably less than 400 xcexcm and most preferably less than 125 xcexcm.
The particles prepared as described hereinabove can then be formulated by conventional techniques into pharmaceutical dosage forms such as tablets and capsules.
It will be appreciated that a person of skill in the art will be able to optimize the parameters of the solid dispersion preparation techniques described above, such as the most appropriate solvent, the working temperature, the kind of apparatus being used, the rate of spray-drying, the throughput rate in the melt-extruder
The water-soluble polymers in the particles are polymers that have an apparent viscosity, when dissolved at 20xc2x0 C. in an aqueous solution at 2% (w/v), of 1 to 5000 mPa.s more preferably of 1 to 700 mPa.s, and most preferred of 1 to 100 mPa.s. For example, suitable water-soluble polymers include alkylcelluloses, hydroxyalkylcelluloses, hydroxyalkyl alkylcelluloses, carboxyalkylcelluloses, alkali metal salts of carboxyalkylcelluloses, carboxyalkylalkylcelluloses, carboxyalkylcellulose esters, starches, pectines, chitin derivates, di-, oligo- and polysaccharides such as trehalose, alginic acid or alkali metal and ammonium salts thereof, carrageenans, galactomannans, tragacanth, agar-agar, gummi arabicum, guar gummi and xanthan gummi, polyacrylic acids and the salts thereof, polymethacrylic acids and the salts thereof, methacrylate copolymers, polyvinylalcohol, polyvinylpyrrolidone, copolymers of polyvinyl-pyrrolidone with vinyl acetate, combinations of polyvinylalcohol and polyvinyl-pyrrolidone, polyalkylene oxides and copolymers of ethylene oxide and propylene oxide. Preferred water-soluble polymers are hydroxypropyl methylcelluloses.
Also one or more cyclodextrins can be used as water soluble polymer in the preparation of the above-mentioned particles as is disclosed in WO 97/18839. Said cyclodextrins include the pharmaceutically acceptable unsubstituted and substituted cyclodextrins known in the art, more particularly xcex1, xcex2 or xcex3 cyclodextrins or the pharmaceutically acceptable derivatives thereof.
Substituted cyclodextrins which can be used include polyethers described in U.S. Pat. No. 3,459,731. Further substituted cyclodextrins are ethers wherein the hydrogen of one or more cyclodextrin hydroxy groups is replaced by C1-6alkyl, hydroxyC1-6alkyl, carboxy-C1-6alkyl or C1-6alkyloxycarbonylC1-6alkyl or mixed ethers thereof. In particular such substituted cyclodextrins are ethers wherein the hydrogen of one or more cyclodextrin hydroxy groups is replaced by C1-3alkyl, hydroxyC2-4alkyl or carboxyC1-2alkyl or more in particular by methyl, ethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, carboxy-methyl or carboxyethyl.
As used hereinbefore, C1-2alkyl represents straight or branched chain saturated hydrocarbon radicals having 1 or 2 carbon atoms such as methyl or ethyl; C1-3alkyl encompasses the straight and branched chain saturated hydrocarbon radicals as defined in C1-2alkyl as well as the higher homologue thereof containing 3 carbon atoms, such as propyl; C2-4alkyl represents straight or branched chain saturated hydrocarbon radicals having from 2 to 4 carbon atoms such as ethyl, propyl, butyl, 1-methyl-propyl and the like.
Of particular utility are the xcex2-cyclodextrin ethers, e.g. dimethyl-xcex2-cyclodextrin as described in Drugs of the Future, Vol. 9, No. 8, p. 577-578 by M. Nogradi (1984) and polyethers, e.g. hydroxypropyl xcex2-cyclodextrin and hydroxyethyl xcex2-cyclodextrin, being examples. Such an alkyl ether may be a methyl ether with a degree of substitution of about 0.125 to 3, e.g. about 0.3 to 2. Such a hydroxypropyl cyclodextrin may for example be formed from the reaction between xcex2-cyclodextrin an propylene oxide and may have a MS value of about 0.125 to 10, e.g. about 0.3 to 3.
Another suitable type of substituted cyclodextrins is sulfobutylcyclodextrines.
The ratio of active ingredient over cyclodextrin may vary widely. For example ratios of 1/100 to 100/1 may be applied. Interesting ratios of active ingredient over cyclodextrin range from about 1/10 to 10/1. More interesting ratios of active ingredient over cyclodextrin range from about 1/5 to 5/1.
It may further be convenient to formulate the present azole antifungals in the form of nanoparticles which have a surface modifier adsorbed on the surface thereof in an amount sufficient to maintain an effective average particle size of less than 1000 nm. Useful surface modifiers are believed to include those which physically adhere to the surface of the antifungal agent but do not chemically bond to the antifungal agent.
Suitable surface modifiers can preferably be selected from known organic and inorganic pharmaceutical excipients. Such excipients include various polymers, low molecular weight oligomers, natural products and surfactants. Preferred surface modifiers include nonionic and anionic surfactants.
Yet another interesting way of formulating the present compounds involves a pharmaceutical composition whereby the present antifungals are incorporated in hydrophilic polymers and applying this mixture as a coat film over many small beads, thus yielding a composition which can conveniently be manufactured and which is suitable for preparing pharmaceutical dosage forms for oral administration.
Said beads comprise a central, rounded or spherical core, a coating film of a hydrophilic polymer and an antifungal agent and a seal-coating layer.
Materials suitable for use as cores in the beads are manifold, provided that said materials are pharmaceutically acceptable and have appropriate dimensions and firmness. Examples of such materials are polymers, inorganic substances, organic substances, and saccharides and derivatives thereof.
The pharmaceutical compositions mentioned above may also contain a fungicidally effective amount of other antifungal compounds such as cell wall active compounds. The term xe2x80x9ccell wall active compoundxe2x80x9d, as used herein, means any compound which interferes with the fungal cell wall. Appropriate antifungal compounds for use in combination with the present compounds include, but are not limited to, known azoles such as fluconazole, voriconazole, itraconazole, ketoconazole, miconazole, ER 30346, SCH 56592; polyenes such as amphotericin B, nystatin or liposomal and lipid forms thereof, such as Abelcet, AmBisome and Amphocil; purine or pyrimidine nucleotide inhibitors such as flucytosine; polyoxins and nikkcomycins, in particular nikkomycin Z or nikkomycin K and others which are described in U.S. Pat. No. -5,006,513 or other chitin inhibitors; elongation factor inhibitors such as sordarin and analogs thereof; mannan inhibitors such as predamycin; bactericidal/permeability-inducing (BPI) protein products such as XMP.97 or XMP.127; complex carbohydrate antifungal agents such as CAN-296; (1,3)-xcex2-glucan synthase inhibitors including papulacandins, aculeacins, and echinocandins.
It is especially advantageous to formulate the aforementioned pharmaceutical compositions in unit dosage form for ease of administration and uniformity of dosage. Unit dosage form as used in the specification and claims herein refers to physically discrete units suitable as unitary dosages, each unit containing a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Examples of such unit dosage forms are tablets (including scored or coated tablets), capsules, pills, suppositories, powder packets, wafers, injectable solutions or suspensions, teaspoonfuls, tablespoonfuls and the like, and segregated multiples thereof.
Those of skill in treating warm-blooded animals suffering from diseases caused by fungi could easily determine the therapeutically effective daily amount from the test results given herein. In general, it is contemplated that a therapeutically effective daily amount would be from 0.05 mg/kg to 20 mg/kg body weight.